25 research outputs found
Hyperonic mixing in five-baryon double-strangeness hypernuclei in a two-channel treatment
Properties of hypernuclei H and He are studied in a two-channel approach with explicit treatment of
coupling of channels ^3\text{Z}+\Lambda+\Lambda and \alpha+\Xi. Diagonal
\Lambda\Lambda and coupling \Lambda\Lambda-\Xi N interactions are derived
within G-matrix procedure from Nijmegen meson-exchange models. Bond energy
\Delta B_{\Lambda\Lambda} in He exceeds significantly
that in H due to the channel coupling. Diagonal \Xi\alpha
attraction amplifies the effect, which is sensitive also to \Lambda-core
interaction. The difference of the \Delta B_{\Lambda\Lambda} values can be an
unambiguous signature of the \Lambda\Lambda-\Xi N coupling in \Lambda\Lambda
hypernuclei. However, improved knowledge of the hyperon-nucleus potentials is
needed for quantitative extraction of the coupling strength from future data on
the \Lambda\Lambda hypernuclear binding energies.Comment: 11 pages with 3 figures; Phys. Rev. C, accepte
Consistency of Lambda-Lambda hypernuclear events
Highlights of Lambda-Lambda emulsion events are briefly reviewed. Given three
accepted events, shell-model predictions based on p-shell Lambda hypernuclear
spectroscopic studies are shown to reproduce the Lambda-Lambda (LL) binding
energies of LL10Be and LL13B in terms of the LL binding energy of LL6He.
Predictions for other species offer judgement on several alternative
assignments of the LL13B KEK-E176 event, and on the assignments LL11Be and
LL12Be suggested recently for the KEK-E373 HIDA event. The predictions of the
shell model, spanning a wide range of A values, are compared with those of
cluster models, where the latter are available.Comment: Based on talk given by Avraham Gal at EXA 2011, Vienna, September
2011; Proceedings version prepared for the journal Hyperfine Interactions;
v2--slight changes, matches published versio
S-wave Pairing of Hyperons in Dense Matter
In this work we calculate the gap energies of hyperons in
neutron star matter. The calculation is based on a solution of the BCS gap
equation for an effective G-matrix parameterization of the
interaction with a nuclear matter background, presented recently by Lanskoy and
Yamamoto. We find that a gap energy of a few tenths of MeV is expected for
Fermi momenta up to about 1.3 fm. Implications for neutron
star matter are examined, and suggest the existence of a
superfluid between the threshold baryon density for formation and the
baryon density where the fraction reaches .Comment: 16 pages, Revtex, 9 figures, 33 reference
On the Surface Structure of Strange Superheavy Nuclei
Bound, strange, neutral superheavy nuclei, stable against strong decay, may
exist. A model effective field theory calculation of the surface energy and
density of such systems is carried out assuming vector meson couplings to
conserved currents and scalar couplings fit to data where it exists. The
non-linear relativistic mean field equations are solved assuming local baryon
sources. The approach is calibrated through a successful calculation of the
known nuclear surface tension.Comment: 12 pages, 9 figure
Production of {\pi}+ and K+ mesons in argon-nucleus interactions at 3.2 AGeV
First physics results of the BM@N experiment at the Nuclotron/NICA complex
are presented on {\pi}+ and K+ meson production in interactions of an argon
beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 AGeV. Transverse
momentum distributions, rapidity spectra and multiplicities of {\pi}+ and K+
mesons are measured. The results are compared with predictions of theoretical
models and with other measurements at lower energies.Comment: 29 pages, 20 figure
Phenomenological model for the Kbar N --> K Xi reaction
A phenomenological model for the Kbar N --> K Xi reaction is suggested. The
model includes s and u channel exchanges by Lambda, Sigma, Sigma(1385), and
Lambda(1520) and s channel exchanges by above-threshold hyperonic resonances.
Explicit expression for the propagator for a particle with spin 7/2 is
presented. High-mass and high-spin resonances play a significant role in the
process. We deal with the whole set of existing experimental data on the cross
sections and polarizations in the energy range from the threshold to 2.8 GeV in
the center-of-mass system and reach a good agreement with experiments.
Applications of the model to other elementary reactions of Xi production and to
Xi hypernuclear spectroscopy are briefly discussed.Comment: Published version; minor change
Proton drip line for light hypernuclei
We determine the location of the proton drip line for light and hypernuclei. While it is already known for , our main focus is the range, and further conclusions are drawn for proton-rich hypernuclei up to . binding energies from the Skyrme-Hartree-Fock calculation and the energies of unstable nuclei known experimentally are used. It is shown that C, C and O with unstable nuclear cores are bound whereas B, N, O and N are not. Boundness of B remains questionable. Among heavier systems, F, Na and Mg are shown to be the possible candidates for bound hypernuclei